Abstract: A toner pack for use with the developing device includes a toner box in which toner is stored and which is detachably set at the developing device, an endless seal sheet a portion of which is peelably bonded to the toner box to cover an opening of the toner box, a flat cylindrical cover member through which that portion of the endless seal sheet which does not cover the opening of the toner box is freely movably passed, and a pull portion which is freely movably passed through the cover member and one end of which is made continuous from the endless seal sheet.

Abstract: An electrophotographic apparatus has its electrophotographic component parts divided into three units consisting essentially of a developing unit A, a photoreceptor unit B and a toner cartridge unit C. Each of the units is capable of being detached from and reattached to the main body of the apparatus while maintaining the required relative positions. The service lives of the units are set in such a manner that the ratio therebetween is represented as a ratio between integers, and the relationship therebetween in magnitude satisfies the relationship of the service life of the developing unit A.gtoreq.the service life of the photoreceptor unit B.gtoreq.the service life of the toner cartridge unit C. Thus, the apparatus enables its maintenance to be performed easily and economically without requiring any increase in the size and the cost of the electrophotographic mechanisms.